<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    </script>
</head>
<body>
<p>1</p>
<p>2</p>
<p>3</p>
<p>4</p>

<div id="div1">
    <p>xx</p>
</div>
<script src="./jquery-3.2.1.js"></script>
<!-- <script src="./my-jquery.js"></script> -->
<script>
    var $p = $('p')
    $p.css('color', 'red') // .css是原型方法
    console.log($p.html()) // .html是原型方法
    console.log($p) // .html是原型方法
    var $div = $('#div1')
    $div.css('fontSize', '20px') // .css是原型方法
    console.log($div.html()) // .html是原型方法
</script>
</body>
</html>